More than 350,000 adults elect primary Total Knee Replacement (TKR) surgery each year to eliminate knee arthritis pain that persists despite comprehensive medical treatment. The 2003 NIH TKR Consensus Panel concluded that TKR effectively eliminates knee pain with few complications. In contrast to the uniform surgical outcomes and pain relief, significant variation remains in functional outcome after TKR. An estimated 15-30 percent of patients report no clinically significant functional improvement at 12 months after. TKR. No one patient attribute or surgical factor satisfactorily accounts for this variation. Our pilot data documents that higher quantities of post-TKR exercise and stronger pre-TKR emotional health are associated with greater improvement in function after TKR. Based on evidence in non-surgical arthritis care, we hypothesize that a peri-TKR self-care support intervention designed to enhance patient self-efficacy for independent exercise and activity will significantly increase post-TKR physical function (measured by SF-36/ Physical Component Score) and knee function (measured by WOMAC score) at 6 and 12 months. In addition, we hypothesize that increased arthritis self-efficacy at 8 and 26 weeks post-TKR (measured by Stanford scale) and increased knee exercise (quantity, frequency) and activity (mean steps/day) at 8 and 26 weeks will be associated with improved 6 and 12 month function after TKR. The proposed research will develop a 12- session pre and post-TKR patient intervention (English and Spanish) incorporating proven arthritis self-care elements. Telephone delivery will accommodate patients' physical limitations. The program's efficacy will be tested in a surgeon blinded RCT allocating a stratified random sample to intervention (n=90) and usual care (n=90). The intervention is theory-based and extends successful health-behavior change intervention algorithms and established arthritis self-management strategies to the peri-TKR patient. This research is the first to extend behavioral science theory to the peri-operative TKR patient and extrapolates a chronic care model to orthopedic practice. This peri-TKR intervention changes the paradigm for TKR care to include patient self-management support for independent activity and exercise to assure uniform, optimal improvement in post- TKR function and patient autonomy- the ultimate goals of TKR. [unreadable] [unreadable] [unreadable]